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    <script type="text/javascript">

        //数据代理：通过一个对象代理另一个对象中属性的操作（读/写）
        let obj1 = {x:100}
        let obj2 = {y:200}

        //此处函数对obj2进行操作，并且追加x属性
        Object.defineProperty(obj2,'x',{
            get(){
                return obj1.x
            },
            set(value){
                obj1.x = value
            }

        }
        )
    </script>
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